Sulfurized sperm oil lubricating oil additives stabilized with sulfites



Patented Sept. 28, 1954 SULFURIZED SPERM OIL LUBRICATING OIL ADDITIVES STABILIZED WITH SULFITES Ethel J. Corcoran, Staten Island, N. Y., and Edward P. Cashman, Ba Standard Oil Develo ration of Delaware yonne, N. J'., assignors to pment Company, a corpo- No Drawing. Application December 13, 1950, Serial No. 200,690

3 Claims.

This invention relates to lubricating oil compositions. Particularly the invention relates to lubricating oil additives having the characteristic of improving qualities of lubricants into which they have been incorporated. More particularly the invention relates to a process for the treatment of additive materials which contain combined sulfur in such a manner as to stabilize them against the evolution of hydrogen sulfide.

In many types of modern machinery, very high unit pressures occur between the adjoining parts of moving metallic surfaces. Unless such surfaces are eifectively and continuously lubricated, rapid wear and early destruction occur. At the pressures which are sometimes employed, particularly when operating at high speeds or high torques and high temperatures, conditions arise under which ordinary lubricants are not capable of maintaining protective lubricating films. In such cases the lubricating films of oil are commonly supplemented or replaced by thin layers of chemical compounds which are formed on and from the metal of the cooperating machine parts. Thus, as is well known in the art, certain substances, such as sulfur, chlorine, phosphorus, and the like, when added to lubricating oils and when subjected to high temperatures generated over limited areas by the pressure between moving parts, combine in some chemical manner with the metal of such parts to produce protective films of microscopic thickness which adhere tenaciously to the metal surfaces, and prevent metal to metal contact.

Lubricants of the general character referred to above may consist of blends of a petroleum oil with a saponifiable oil containing as extreme pressure agents, either as free elements or as chemical compounds, sulfur, chlorine, phosphorus and the like. The added compounds are usually and preferably somewhat inactive chemically at ordinary operating temperatures, becoming more reactive with the metal surfaces, however, when such surfaces are subjected to the high temperatures which result from the frictional heat generated by the transmission of power through a gear train.

In the past it has been necessary to compromise between extreme pressure additives which, on the one hand, are effective, when needed, to provide the type of protecting film mentioned above, but are objectionably corrosive over a period of time to metals such as copper and steel, and those which, on the other hand, are non-corrosive but are only moderately effective as extreme pressure agents.

Presumably, the microscopically thin protective films which are formed on metal surfaces in the manner referred to above consist of metal sulfides, chlorides, phosphides and the like. Thus, when sulfur, chlorine, phosphorus and like materials are used on steel gears (such as for example, hypoid gears in automobile driving axles), where unit pressures are very high at times, iron sulfides, chlorides, phosphides and the like are formed. Analogous compounds are formed with other metals.

Numerous compounds have been used in the past for the purposes described above. Among them are reaction products of various organic materials, particularly hydrocarbons, with substances such as the phosphorus sulfides, elemental phosphorus, arsenic, selenium, lead compounds, oxides of phosphorus, various chlorides, etc. It is well known, for example, that phosphorus sulfides may be dissolved in and/or reacted with various fatty bodies such as fatty oils, fatty acids, sulfurized fatty oils, halogenated hydrocarbons and the like to impart E. P. characteristics thereto. Such compositions may then be used directly as extreme pressure lubricants or, more commonly, they are supplied as concentrated additives for use in small quantities in mineral oil base lubricants.

One of the features commonly objectionable in these extreme pressure additive materials which contain combined sulfur is their tendency to evolve hydrogen sulfide on continued standing, In addition to the diminution of the combined sulfur content of the additive material this hydrogen sulfide evolution is objectionable from the standpoint of the disagreeable odor attendant.

Previous attempts to eliminate this undesirable hydrogen sulfide evolution have included air blowing, nitrogen blowing, caustic washing, soda ash washing, and the like. Some of these procedures have utility but ordinarily on continued standing the odor of hydrogen sulfide may be detected or its presence indicated by the standard hydrogen sulfide test, introducing moist lead acetate paper into the area immediately above the additive material.

It has now been found that the sulfur content of these extreme pressure additive materials may be substantially completely stabilized by a process of admixing with the additive material sodium sulfite or sodium hydrosulfite and heating for the desired period of time at a temperature suitable to stabilize the combined sulfur.

In general, the process of this invention is a simple one capable of being carried out in any standard plant equipment, a fact which adds to its utility. The additive material to be treated, either in the form of an oil concentrate containing from 20% to 90% by weight of the additive material or the crude material per se, is admixed with from 0.5% to 6.0% by weight based on the weight of the total mixture of sodium sulfite or sodium hydrosulfite. Although it is preferred that the treating agent be in solid form when it is admixed with the material to be treated, a water solution of the treating agent may be used.

The mixture of the treated material and the treating agent is stirred to obtain uniform dispersion and the temperature is then raised to one within a range of from 150 to 250 F., preferably 175 F. to 225 F. The temperature of the mixture is maintained at this level for a period of time within a range of from 5 minutes to one hour, preferably from to 30 minutes. It will be appreciated that these temperature and time limitations will be varied depending upon the total combined sulfur content of the material undergoing the treatment or upon the type of combined sulfur. When higher amounts of combined sulfur are present in the additive materials more drastic treatment times and temperatures are required.

As was mentioned above, sodium sulfite or sodium hydrosulfite either in the solid form or in the form of a water solution, may be used as the treating agent. When the solid sodium sulfite or sodium hydrosulfite is used the reaction mixture is filtered to remove any solid material remaining. When a water solution of a treating agent is used it is found advantageous to supply the reaction mixture that has been cooled to a vacuum distillation step in order to completely remove any residual water solvent remaining. These separation steps are, of course, known to the art and do not form an integral part of this invention,

Any of the well known extreme pressure agents containing therein combined sulfur may be improved by the process of this invention. It has outstanding utility, however, when applied to sulfurized and/or sulfurized-phosphorized fatty materials such as sperm oil, lard oil, dipentene, and like materials.

In order to more effectively illustrate the process of this invention the following examples are set forth. It is to be understood, of course, that these examples are merely illustrative and in no way limit the concept of the instant invention.

EXANEPLE I 78 pounds of sulfurized sperm oil containing 6.4% sulfur was charged to a gallon glass Pfaudler reactor. There were admixed with the sperm oil 176 g. of phosphorus sesquisulfide. The temperature of the reactor was then raised to about 220 F. and held for one hour at that temperature. An additional temperature increase to 300 F. was brought about over a period of one hour and held at that point for 4 hours. The reaction mixture was then cooled under 22 inches of mercury vacuum to room temperature and stored in a 5 gallon can.

EXAMPLE II In this example '78 pounds of sulfurized sperm oil, sulfur content 6.4%, was admixed with 266 g. of phosphorus sesquisulfide in a 15 gallon glass Pfaudler reactor. The temperature was raised to about 220 F. and held for one hour, then raised to 300 F. over a period of one hour and held at that point for 4 hours. The reaction mixture was then cooled to 190 F. and g. of solid sodium hydrosulfite was added. With agitation the temperature was raised to 200 F. and held at that point for 15 minues. The reaction mixture was then cooled to room temperature under 22 inches of mercury vacuum and the cooled product was stored in a 5 gallon drum.

EXAIVIPLE III In this example '78 pounds of sulfurized sperm oil, sulfur content 6.4%, was admixed with 266 g. of phosphorus sesquisulfide. The treating agent used was 88 g. of sodium hydrosulfite dissolved in 3% pounds of water. The same procedure. as used in Example II above was followed in this example. In this case the water used as a solvent for the sodium hydrosulfite was removed during the vacuum step.

EXAMPLE IV Following the procedure outlined in Example II above, the following proportions of reagents were used in an additional experiment: 7 8 pounds of sulfurized sperm oil, 6.4% sulfur, 266 g. of phosphorus sesquisulfide, and 1'75 g. of sodium sulfite in solid form.

The samples prepared in accordance with Examples I through IV above were tested periodically for hydrogen sulfide by means of moist lead acetate paper. In this test the lead acetate paper was subjected to the area in the 5 gallon drum above the level of the treated material. The results of the test are set out in Table I below.

Table I Hydrogen Sulfide Evolution Sample No.

After 4 Months 1 After 2 days, strong evolution.

EXAMPLE V A second portion of the product of Example I was admixed with 1% solid sodium hydrosulfite and heated for 15 minutes at a temperature of 200 F. This sample was likewise cooled to room temperature and the solid particles removed by filtration.

To show that the treatment of this invention efiects only the hydrogen sulfide evolution on sions for controlling speed of rotation, the slipping velocity, and the rate of applying pressure at the line of contact between the rotating test specimens. The oil blend to be tested is placed storage, the three portions of the product of Ex- 5 in a cup in which the two cylindrical test speciample I, that is, that portion not treated, the mens are rotated. After a break-in period an portion treated with sodium sulfite, and the automatic loading device is operated at a desired portion treated with sodium hydrosulfite, were rate of loading until the test specimens are analyzed for sulfur and phosphorus content, scored. The machine is then stopped and the tested for viscosity at 100 F. and 210 F., and an SAE rating is noted. The higher the SAE rating, A. P. I. gravity determination made. the more load the test specimens sustained with- In addition to these gravity and viscosity deout scoring. terminations, the well known copper strip test The blends prepared as described above gave was run on these three samples. This test, which the following SAE: machine test data: gives an indication of the corrosivity of the material, is described in detail in the C. R. 0. Hand- Table III book, 1946 edition, pp. 445-447, and is designated as C. R. C. Test L16-445. The test is briefly as follows:

A piece of copper sheet M by 3" is polished 20 Example 13% with steel wool. The strip is then placed in a test tube and covered with the oil blend to be H t t 7 tested. The tube is placed in an oil bath at the Yea 5 desired temperature and held there for the der t?k, r ir fin h if fiifit3lIII ii sired time. The copper strip is then rinsed with naphtha and inspected. The rating scale is from 1 to 10, the numbers increasing With t e co It will be noted from the data in Table III rosivity of the compound to copper increasing above that the extreme pressure properties of with the activity of the sulfur The lesser the the treated material are substantially equal to rating number, the lighter the test strip. A ratthose of the untreated materia1s ing of 1 would be given a test strip having substantially no discoloration after the test, whereas EXAMPLE VII the rating of 10 would be given to a completely darkened test strip showing pitting. The barium salt of diisobutyl phenol sulfide The n blend of Examples 1, v and VI was was dissolved in a phenol extracted Mid-Conbjected t the above described copper strip tinent distillate having a viscosity of 210 F. of 43 test for one hour t a temperature of 250 S. U. S. and a viscosity index of 112 to result The data obtained in the above described tests in a co e tration of the salt in oil. This are set out in Table II below: oil concentrate was then treated with 4 weight Table II reath Example No Perzent Perlcent ag? g p at 100 at 210 after after4 F. F. mos. mos.

I (untreated) 6. 4 0 26 836 118.4 19. 0 5 V 6.2 0 26 830 117.6 19.0 5 none none. VI 6.1 0.23 824 117.1 19.0 5 none none.

1 After 2 days, strong evolution.

To show that the extreme pressure additive per cent Pass by heating to 300 F. for 420 minmaterials after treatment by the process of this utes. invention lose none of their extreme pressure resisting characteristics, the following tests were EXAMPLE VIII made- 100 parts of the material of Example VII was The matehals of Examhles F and h admixed with 5 parts of solid sodium sulfite in blended to 10% concentration in a test 011 which a glass Pfaudlel. reactor. The reactor was heated was Prepared by blending dewaxed, acid treated to 220 F. with stirring and maintained at that Pennsylvania distillate and a propane deasphalttemperature for one hour The material was ed crude residuum The blend a a Vlscoslty at then allowed to cool and pressed to remove resid- 21U F. Of 126.8 S. U. S., a VlSCOSltY at 100 F. Of ual solid Sodium sulfite particles. 1845 S. U. S., an A. P. I. gravity of 25.4 at 60 F., and an ASTM pour point of +10 F. The blends 5 EXAMPLE of these materials were then submitted to the standard SAE Extreme Pressure Machine Test. Following the procedure of p e V II above. This test is described in the C. R. C. Handbook 100 Parts 9 the material Q Example VII was mentioned above on pp. 458-462 and is designated edmlxed wlth 5 Parts of Sohd Sodlum hydrosulas c. R. 0. Test 11-17-545. The test is described 0 fite and contacted for one 110111 at generally as follows; The materials of Examples VII, VIII, and IX The test machine is essentiany a device in were subjected to sulfur and. phosphorus deterwhich two cylindrical test specimens are rotated minetions, a viscosity determination. t pp r in lined contact with each other in opposite di- Strip Test described in connection with Examrections. The machine is equipped with proviples I through VI above, and a storage test for hydrogen sulfide evolution. The results of these determinations are set out in Table IV below:

Table IV Viscosity Example Per- Per- Cu .N-o. cent S cent P 10 Strip HES Evolutmn VII. r 5. 8 0.85 129. 9 8 Strong. VIII n 6.0 O. 85 131. 7 7 No Has-7 days. IX 5. 3 0.95 130. 8 7 No 1125-7 days.

The material presented in Table IV above clearly points out the advantages of the process of this invention when applied to extreme pressure agents of the disulfide type.

EXAMPLE X '70 parts of dipentene and 30 parts of sulfur were reacted in the presence of a catalyst (a mixture of mercaptobenzothiazole and diphenyl guanidine) at a temperature of 350 F. for hours. The product was cooled and pressed.

EXAMPLE XI 100 parts of the sulfurized dipentene of Example X were admixed with one part of solid sodium sulfite in a Pfaudler reactor. The materials were heated to about 220 F. and held for one hour at that temperature. The reaction material "was then cooled and pressed to remove any unreacted particles of sodium sulfite.

EXANIPLE XIII Table V Example No. Pergent ifigi g g a H23 Evolution 22. 2 47. 9 8 Strong-2 days. 22.0 48. 3 8 No H2S-9 days. 21. 4 47.9 18 Lt. H2S--9 days.

It will be noted that while the viscosity, the percentage of sulfur, and the copper strip rating remains the same, the hydrogen sulfide evolution is materially improved by subjecting the sulfurized dipentene to the process of the instant invention.

To summarize briefly, this invention relates to a process for the treatment of lubricant additives containing therein combined sulfur which comprises admixing with the additive materia1 from 0.5% to 6.0% by weight based on the weight of the total composition of a material of. the class consisting of sodium sulfite and sodium hydrosulfite, either in the form of a solid or a solution thereof, and heating the resulting mixture for from 5 minutes to one hour at a temperature of from to 250 F. Although the invention is applicable to any lubricant additive containing combined sulfur, regardless of any other combined elements, it is particularly applicable to fatty materials containing combined therein phosphorus and sulfur.

What is claimed is 1. A process for the stabilization of the sulfur content of lubricating oil additives of the class consisting of sulfurized and sulfurized-phosphorized sperm oil which comprises admixing with said additive a material of the class consisting of sodium sulfite and sodium hydrosulfite, heating the mixture to a temperature within a range of from 150 to 250 F. for from 5 minutes to one hour, and separating the improved additive from the mixture.

2. A process for the stabilization of sulfurized sperm oil containing about 6.4% combined sulfur against hydrogen sulfide evolution which comprises admixing with said fatty material from .5 to 6.0% by weight of a material of the class consisting of sodium sulfite and sodium hydrosulfite, heating the resulting mixture to a temperature within a range of from 150 to 250 F. for from 5 minutes to one hour, and separating the improved additive from the mixture.

3. A process for the stabilization of a phosphosulfurized sperm oil containing from 5% to 8% sulfur and from 0.1% to .5% phosphor-us against hydrogen sulfide evolution which comprises admixing with said sperm oil from .5 to 6.0% by weight of a material of the class consisting of sodium sulfite and sodium hydrosulfite, heating the resulting mixture for from 10 to 30 minutes at a temperature of from to 225 F., and separating the stabilized sperm oil from the mixture.

References Cited in the file of this patent UNITED STATES PATENTS Alexander Jan. 9, 1951 

1. A PROCESS FOR THE STABILIZATION OF THE SULFUR CONTENT OF LUBRICATING OIL ADDITIVES OF THE CLASS CONSISTING OF SULFURIZED AND SULFURIZED-PHOSPHORIZED SPERM OIL WHICH COMPRISES ADMIXING WITH SAID ADDITIVE A MATERIAL OF THE CLASS CONSISTING OF SODIUM SULFITE AND SODIUM HYDROSULFITE, HEATING THE MIXTURE TO A TEMPERATURE WITHIN A RANGE OF FROM 150* TO 250* F. FOR FROM 5 MINUTES TO ONE HOUR, AND SEPARATING THE IMPROVED ADDITIVE FROM THE MIXTURE. 